Sample

#loadLibrary 'KcSysLib'
#loadLibrary 'KcStrLib'
#loadLibrary 'KcRexLib'
 
main()
{
   const pattern = '\\(sim[a-z]le\\) \\1';
   const string  = 'a very simple simple simple string';
 
   sysLog('compile regular expression');
   var rx = rexOpen(pattern);
   var match[6][2];
 
   sysLog('find and display match');
   sysLogLevel(+1);
   var m = rexMatch(rx, string, 6, match);
   if (m) {
      for (var i = 0; i < m; i++)
         sysLog(
            match[i][0]+' '
            +match[i][1]+' \''
            +strSubString(string,match[i][0], match[i][1])
            +'\''
         );
   } else
      sysLog('no match found');
   sysLogLevel(-1);
 
   sysLog('close and release mem');
   rexClose(rx);
} // main

When executing this sample the output will be:

compile regular expression
find and display match
  8 13 'simple simple'
  8 6 'simple'
close and release mem